Airdam with or without splitter?

[manta22]

One loses even more cool points by driving over his crankshaft   

Regards, Neil  Tucson, AZ

[jacksoni]

When we had the Bugeye in the windtunnel, we built a lower dam/splitter to go under the nose. When first attached the angle of attack, if you will, of the splitter was not correct and it made drag and lift worse. Tech said something wrong, that shouldn't be. We repositioned it for proper location and lift particularly, and drag ( a little as I remember, haven't gone back to notes-not sure I can find them   ) improved. Pay attention to the splitter positioning and I triple the comments about the crunchies. But since you are running ECTA only should not be a problem. Track there is smooth but still some bumps here and there on track or return road or heaven forbid a foray into the grass might make it a snow plow and ruin your beautiful craftsmanship. A flexible lip as suggested may be a good idea.

[Rex Schimmer]

Looking through Simon Mcbeath's "Competition Car Aerodynamics" his info on spliters is that they can add up to 10% additional down force with almost zero increase in drag, looks like a free lunch! Does your spliter extend behind the air dam? forming a flat panel between the two ends? If it does you need to provide this panel with some additional stiffness as it will suck down to the ground pretty easily.

Since you are running "modified sports" do you plan to add some head light covers?

Rex

[RebekahsZ]

The splitter lip will be composite fiberglass over a 1/2-inch foam board-fiberglass on top and bottom. I think it will be plenty rigid. Just not very resistant to impact, therefore it will be 3" off the pavement. Who knows-it may be a waste of time, but I will let everybody know how it turns out. I like this forum group already (similar sense of humor, etc).  The headlight covers arrived yesterday!

[WZ JUNK]

I made a fiberglass splitter for Hooley.  We lost it on the first pass at Bonneville.  His car is very low, and at high speed the splitter became a grader blade for a short time.

John

[RebekahsZ]

Splitter hit runway on first pass at 174 mph. Cut off splitter and airdam hit pavement on 167 mph pass. Airdam static height was 3". Looks like time to add some spring rate.

[manta22]

Could be worse-- could be lift. 

Regards, Neil  Tucson, AZ

[Captthundarr]

You can add a considerable amount because of the area of your hood. We / I need to do the same on our camaro for different reasons. We cut the front tire on the camaro because the nose took a serious dive with the chute and new brakes. Good meeting you and thanks for tire offer.

Frank Hartman
Jackscratch racing on facebook

[SPARKY]

you guys are commenting on why so many of us run solid axels in LSR

[RebekahsZ]

Yeah, I'm finding the limits/frustrations of trying to multi-sport a vehicle.  This car has been my daily driver, drag car, autocross car, HPDE track car, and now my landspeed car.  My clutch hydraulics blew on the trip home, so I will be dailying the Z until I fix the truck.  It is fun at all, but kinda sucks at all too. Definitely seeing the wisdom of a solid axle front and back.  So much to learn.  I never dreamed that this car would be this fast with a motor that I yanked out of a junkyard and just stuck in there.  Last month, I don't recall the car being as twitchy as it was this month.  May be that I was too adrenaline-ed up last month and that I'm just seeing things that were there all along.  I gained 7mph with that airdam.  Honestly, the airdam may have had nothing to do with it-we had a pretty good tail wind on Saturday-I don't know how strong.  With a BIG headwind on Sunday with a FULL windsock right into our faces, my best was 167.  Sunday was mostly a research day, playing with tire pressures and alignment.  I was so excited when the airdam hit the ground on Saturday that we cut it completely off and re-glassed the defect right in the pits (it was awesome wrenching hard with my friends).  We should have slowed down and done some video documentation before cutting it off.  I plan to come back next year with 400-500 pound springs and as much caster as I can screw into it.  I will bring a variety of bolt-on splitters and a couple of different rear spoilers.  I'm at the limit of my safety/speed class at 174 anyway (was getting hassled the whole meet for not tossing a chute)-no reason to try to go faster until the car feels more safe.  I will plan next year to be all TnT.  If I can get this handling stuff sorted next year, then will do the safety for 200 the following winter and add some laughing gas.  Was great to get to know a bunch of good guys and gals.  BTW-as far as the airdam/radiator block-off and heat is concerned:  With a starting coolant temp of 194-196, with a small opening in the airdam, coolant temps were 199 as I rolled off the track, and rose to 207 in impound and at the timeslip trailer.  With the opening blocked, temps were 225-230 as I rolled off the track and rose to as much as 244 until I got the hood off and let her cool down at idle.  On the headwind day, the car ran the same 167 with or without the radiator block-off plate installed.  Did not test it on the tail wind day-wish I had.  More to learn.

[SPARKY]

your issue may be scrub related and not caster---caster just helps hands off-- not necessarily hands on  YMMV

[RebekahsZ]

Ok. Hmm..my understanding of scrub is pretty rudimentary. But if I wanted to reduce scrub without totally redesigning my suspension, I would need to increase my backspacing effectively moving the tires contact toward the center of the car, right?  I might also accomplish the same thing by reducing negative camber?

[manta22]

You might try finding an old book called "How to Make Your Car Handle" by Fred Puhn. It is pretty basic but explains suspension geometry pretty well. A computer software program "Suspension Analyzer" is a great way to find out what your car is actually doing and you can move things around on-screen easily to see their effects on the geometry. They have a library of stock geometries-- maybe a Z.

Regards, Neil  Tucson, AZ

PS

Sparky, a straight axle may be simpler but it isn't a sure thing. Even a straight axle needs to be sprung correctly. A couple of years ago I attended an open house hosted by a well-known LSR team that was running a fast roadster. One driver complained that the car seemed even twitchier than roadsters usually are. Their problem was clear (maybe there were others, too)-- they had used a Panhard bar to locate the rear axle laterally but the mounting point on the chassis was way higher than on the axle. As the rear moved up and down it was pushing the axle left & right. Not good. Putting the mounting points closer to the same height made a big difference.

[tauruck]

My experience with this subject has been on circuit racing and I built ''air dams''/splitters for Trans Am type cars, Porsche etc.

Also built a complete front end for an 8 second Mazda 3 drag car but it has a floor tray under the front end.
It covers the bottom of the engine bay and the splitter extends about 1" forward. No lift or other problems reported.
IMO the whole thing hinges off angle of attack and spring rate. What happens to the air that gets under your Datsun when it gets by the flat plate airdam during bump and rebound?. What's it doing in the area around the original valance etc???.

I guess Woody would have the right answers.

[RebekahsZ]

Yup to all the above. Only way to know is to model or test. Woody, A2 or both. For now, I'm back to sports car racing so the airdam goes in the shop, toe goes back to zero, landspeed tires go back into baggies and A/C storage. Will pull it all back out when all the local tracks close. Time to put some Hoosier A6s on.